Generally, the conventional microsensor packaging method is carried out in the following manner.
That is, as shown in FIG. 1, on the surface of a device wafer 10 (FIG. 1a), an etching (20) is carried out at a certain thickness so as to install a structure (FIG. 1b). Then as shown in FIG. 1c, a sacrificial layer 30 is formed by carrying out an etching on the already etched part 20, thereby completing the device process. Then on the bottom of a separate package wafer 40 (FIG. 1d), an etching is carried out to form a cavity 50 (FIG. 1e). Then a through contact hole 60 is formed on the package wafer 40 as shown in FIG. 1f so as to make it contacted to the device wafer 10, thereby completing the package wafer process.
Then the protecting package wafer 40 is mounted on the surface of the device wafer 10 by carrying out a bonding step 50' as shown in FIG. 1g. Then in order to form patterns on the surface of the device wafer 10 and on the surface of the package wafer 40, and in order to connect them together, a metal deposition process 70 is carried out on the inside of the contact hole 60 of the package wafer 40 as shown in FIG. 1h, and then, a patterning is carried out, thereby completing the manufacture of the microsensor package.
However, the diameter of the contact hole 60 of the package wafer 40 has to be narrowed according as it is coming down, so that the deposited metal layer 70 would be perfectly continuous in the contact hole 60. Therefore, the lower portion of the contact hole 60 has to have a sharp corner, but the sharp corner is frequently detached during the manufacturing process or after the manufacture.
In the above described cases, when the metal layer 70 is deposited on the inside of the contact hole 60, the deposited metal is short-circuited to the surface of the device wafer 10, with the result that the device shows malfunctions, and thus the device becomes defective.